In general, a conventional linear actuator comprises a driver, a transmission rod and a worm shaft, and a worm gear of the transmission rod linked with the driver, wherein the transmission rod can be extended and contracted by a screw to push an inner tube to achieve the linear actuation effect.
However, most of the conventional linear actuators achieve an extension or a contraction by using a single screw, so that the stroke of extension or contraction is usually limited by the length of the single screw. Even though the stroke of extension or contraction can be increased, it is necessary to increase the length of the screw. As a result, the axial length or size for the installation must be increased when the linear actuator is in a contracted state, and the linear actuator is inapplicable in a space limiting occasion. In addition, a basic structure having dual screws arranged in parallel with each other is also adopted to increase the stroke of extension or contraction of the linear actuator, but the parallel arrangement of the dual screws causes an increase of the width and size for the installation and a decrease of supporting force and stability, and thus the conventional linear actuator requires improvements.
In view of the foregoing problems, the inventor of the present invention based on years of experience in the related industry to conduct extensive researches and experiments to develop a dual-screw linear actuator to overcome the problems of the prior art.